Microelectronic devices are typically contained in a package that allows a connection to another device, such as a printed circuit board. Microelectronic packaging technology, including methods to mechanically and electrically attach a device die or chip (e.g., a microprocessor) to a substrate or other carrier, continues to be refined and improved. Bumpless Build-Up Layer (BBUL) technology is one packaging architecture. Among its advantages, BBUL eliminates the need for traditional die assembly processes, eliminates first-level solder ball interconnections (e.g., flip-chip interconnections), reduces stress on low-k interlayer dielectrics within chips due to die-to-substrate coefficient of thermal expansion (CTE) mismatch, and reduces package inductance through elimination of the package core and flip-chip interconnect for improved input/output (I/O) and power delivery performance.
Microelectromechanical systems (MEMS) devices are micro or nano scale devices that integrate mechanical and electrical elements on a common substrate typically using microfabrication technology commonly employed in integrated circuit (IC) manufacturing. The mechanical elements are fabricated using lithographic processes on a substrate to selectively pattern the devices. Additional layers are often added to the substrates and then micromachined until the MEMS device is in a designed configuration. Exemplary MEMS devices include actuators, sensors, switches, accelerometers, gyroscopes, etc.
Prior work by the inventors includes a number of architectures and techniques for fabricating or otherwise embedding MEMS devices into BBUL packaging architectures, some of which are inductively coupled in one manner or another. For inductively coupled MEMS devices, drive and/or sense transduction between mechanical displacement and electrical circuitry is achieved, at least in part, via a magnetic (B) field. Inductively coupled MEMS devices are also known as “magnetic MEMS” in reference to the presence of a permanent magnet disposed in close proximity to mechanical members of the MEMS device to concentrate magnetic field lines for improved MEMS device sensitivity.
Magnetic fields relied upon by one device, such as a magnetic MEMS device, may however detrimentally impact another device, particularly when devices are embedded in a same package build-up.